This invention relates generally to diode-laser spectrometers and more particularly to a tunable diode-laser heterodyne spectrometer that is modified to provide an apparatus and method to determine the index of refraction of materials such as semiconductor materials and etalon bars. The index of refraction of semiconductor materials such as Ge, Si, HgCdTe, InSb, GaAs and any other material transparent to tunable infrared laser radiation can be accurately determined.
Materials in the form of etalon bars have been used for years for calibrating frequency, in interferometers as standards of length and in conjunction with diode lasers to give alternate transmission and reflection peaks. However, there is no method to accurately determine the index of refraction of these materials. Because of the different doping concentrations used in semiconductor materials there is a need to be able to determine the optical properties simply and accurately for each of these materials.
It is therefore one object of this invention to provide a method of determining the index of refraction of semiconductor materials.
It is another object of this invention to provide a method of determining the index of refraction that is simple and accurate.
It is a further object of this invention to provide a method of determining the index of refraction of materials that are transparent to tunable infrared laser radiation.
It is still another object of this invention to provide an apparatus that can determine the index of refraction of semiconductor materials rapidly, simply and accurately.
It is still a further object of this invention to provide an apparatus that can determine the index of refraction of materials that are transparent to tunable infrared laser radiation.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.